Tim needs help solving math problems using estimations. Estimate each problem below by rounding first, then adding or subtracting.
42 + 27 → __________ + __________ = __________
72 − 16 → __________ − __________ = __________
263 + 541 → __________ + __________ = __________
971 − 316 → __________ − __________ = __________